KISANGANI , 7 April 2011 (IRIN) - An outbreak of cholera that has claimed 51 lives in the eastern Democratic Republic of Congo city of Kisangani since late February could worsen as heavy rains threaten to undermine an emergency chlorination programme, warned health experts.

The outbreak of Vibro cholerae 01 Inaba has led to the hospitalization of 913 people since it was first reported on 23 February.

At present, the outbreak's spread is slowing: 11 new cases were recorded on 6 April and the fatality rate fell from 14.4 to 5.5 percent over the previous three weeks. In mid-March, 189 cases were recorded in a single week in the city's Lubunga district.

It is also confined to Kisangani's five zones. Suspected cases some 125km away from the city tested negative for cholera.

"We are not out of the woods yet," cautioned John Sapu, the doctor in charge of the cholera treatment centre in Lubunga, pointing out that the cholera strain in question was particularly virulent and could survive outside the human body for 15 days. So it will take a fortnight before the effects of the rains and the overall progression of the outbreak can be accurately gauged.

According to World Health Organization official Guy Kalambayi, if the rains do not deliver a new spike in cases, "the spread could be brought under control within a month".

But the lack of a dramatic reduction in the caseload led Leen Verhenne, who works with the Belgian branch of Médecins Sans Frontières, to be cautious.

"This type of epidemic can stay around for the long term and claim many victims," she told IRIN, adding that epidemiological data suggested the principal transmission route was from person to person, rather than via consumption of contaminated water, which generally leads to steeper, shorter peaks in transmission rates.

Hygiene lessons

Mystery still surrounds how the outbreak's patient zero, a 50-year-old woman who had never left Kisangani, became infected. First cases of previous outbreaks tend to involve patients who had travelled from cholera-endemic areas such as Katanga or the Kivu provinces.

Results of tests on 11 of Kisangani's water sources have yet to be released. As a precautionary measure, municipal authorities chlorinated all the city's main sources of water, distributed purification tablets and increased public education about personal and food hygiene.

Of particular concern to health officials is the tradition of mourners embracing the corpses of the deceased before burial; one such incident is known to have caused some early transmissions in this outbreak.

And according to Sapu, some patients "go to a church to get healed, rather than a health centre".

Because the last major outbreak here occurred more than a decade ago, cholera symptoms now often go unrecognized.

"Patients die at home in a sea of their own stool. It's another risk for the community," noted Aimé Lukussa, the doctor in charge of the city's Lubunga Zone. Even though treatment is free, "some come to the health centre too late, when fatal dehydration is too advanced", he added.

Source: The Integrated Regional Information Networks (http://www.irinnews.org )